Apparatus for indicating the pressure of the drill bit or casing on the formation



' Marchxi'30 1926. 1,578,518

H. H. HENSHAW ET AL APPARATUS FOR INDICATING THE PRESSURE OF THE DRILL BIT OR CASING ON THE FORMATION Filed Feb. 4, 1924 2 Sheets-Sheet 1 W attorney a ESSURE OF. THE

FOR 4 March 30 1926.

' H- H. HENSHAW ET AL AP ATUS FOR IGATING THE PR RILL BIT CASING ON THE MATIQN Filed Feb. 4, 192 2 She ets-Sheet 2 H l1 W I Patented Mar. 30, 1926.

UNITED STATES PATENT OFFICE; I

HOLMES n. nnnsrmw, or HOLLYWOOD,

- CALIFORNIA.

ArrAaATUs non. mnicATme Tnn AND WILLIAM H. TAYLOR, or Pomona,

rnnssunnor THE DRILL nrroncasme on THE FORMATION. v

Application filed February 4, 1924. Serial No. 690,608.

To all whom z't may concern: 7 Be it known that'we, HOLMES H. HEN- SHAW and WILLIAM H. TAYLOR, citizens of the United States, residing at Hollywood 6 and Pomona, respectively, both in the county of Los Angeles and State of California, have invented a new and useful Apparatus for Indicating the Pressure of the Drill Bit or Casing on the Formation, of which the following is a specification.

This invention relates to an apparatus whereby the amount of pressure of the drill bit upon the formation, during the drilling A operation, and pressure of .the. casing,while setting said casing, is. indicated, so that the operator may readily regulate the amount of such pressure by appropriate operation of the hoisting drum.

An object of this invention,'as is apparent from the foregoing, is to make it possible to know with what pressure the drill bit is working on the formation. To know thiswill enable the driller to prevent a twist-off of'the drill stem, an occurrence that is quite 2 frequent in the drilling of a well and one that entails considerable expense as itnecessitates a fishing job. 7 v Another object is to" make it possible to know what pressure the casing exerts .on the formation as it descends or on the bottom of the well hole, after being set, thus enabling the operator in the first, instance to discontinue lowering the casing before it sticks fast and, in the second-instance, to suspend the weight of the casing to some extent from the top of the well so as to prevent collapse of the'lower portion of the casing by the weight of the superposed portion.-

' Another object is to provide an apparatus of this type that is of comparatively simple construction and operation.

The accompanying drawings illustrate the invention: v

Fig. 1 is an elevation of an apparatus-em bodymg the invention, one of the drums bein shown in section and portions of the derrick being broken away.

Fig. 2 is an enlarged longitudinal section of the means to indicate the amount of pull exerted on the cable by the part in the well connected therewith, the plane of sectioning being indicated in Fig. 4by the line 2-2. Fig. 3 is a longitudinal section taken on a plane at an angle of forty-five degrees from the plane' of the section 2-2.

Fig. 4 is an enlarged plan section on the lineindicated by 44 of Fig. 3.

It is to be'understood that this invention is used in connection-with a rotary drilling table which, as is Well understood in this art, rotates a drilling stem.- Such stem is indicated in Fig.1 at 5. The rotary drilling table is not illustrated, since its construction and operation are well understood. The drilling stem 5 is connected by any suitable, means, indicated in general by the character 6, to a pulley block 7 throughwhicli is rove a-cable 8 in the customary manner to sup port thedrilling stem or casing. The cable 8 passes to the crown block 9 of the derrick which crown block, as is customary, is pro- 'as the dead end, is adjustably and releasably connected by a suitable clevis 12, or other desired means, to means to indicate 85. the amount of pull exerted on the cable bythe drilling stem or other part in the well connected therewith. These'means may be of any suitable construction and, in-this instance, constitute a hydraulic device, and the. clevis connects with the outer end of a plunger-rod 13 which is slidably'mounted'in the guideway 14 of acylinder 15 provided with a chamber or'chambers 16 in which operate hydraulic plungers 17. The plungers 17 are connected with the plunger-rod 13 by a cross head 18. The various chambers 16 are interconnected by passages 19 so that the pressure in the difit'ererit'cham bers will be equalized. The cylinder 15 and plungers 17 constitute members in telescopic relation. Communicating with one of the chambers 16 is the tube 20 of a hydraulic pressure gauge 21 which may be'calibrated to indicate the pressure in tons or any other denomination.

Any suitable means are provided for anchoring the cylinder 15 so that the pull of the dead end of the cable will be sustained by the fluid cushion a between the members 15, 17. In this particular instance, such means are constructed as follows: Straps 22 extend along opposite sides of the cylinder 15 and are bolted thereto at 23, said straps preferably having their upper ends bent over the upper end of the cylinder as indicated at 24. The straps 22 project a distance beyond the cross head 18 even when the plungers 17 are withdrawn to some extent fronr the cylinder. Near their lower ends the straps 22 are connected by a cross bar 25 which is provided near its opposite ends with holes 26 through which the straps 22 project. Nuts 27, screw-threaded on the straps 22 beneath the cross-bar 25,'hold the cross-bar and straps assembled.

One of the members 15, 17 is anchored and, in this particular instance, the anchorage for the cylinder'15 is constituted by a rotary drum indicated in general by the character 29. This'rotary drum may be, for example, the bull wheel of a Standard drilling rig, but it is to be understood that any suitable drum may be employed. This drum may be operated in a manner well understood in this art, as the anchoring means just described permit rotation of said drum.

It will be noted in Fig. 1 that the dead end of the cable passes through the clamp 12 and is wound on the drum shaft 28. Thus,

' when the apparatus is to be employed, vthe cross bar 25, being first removed, the straps 22 will be positioned astride the shaft, 28 and the cross bar 25 will then be secured in place beneath the shaft 28. Thus, it will be clear, the cable need not be disconnected from the drum 29. p

In practice, assuming that the drill bit has been lowered into contact with the formation and that the drill stem 5 passes through the rotary table bushing, not shown, and is connected with the cable 8, and that the hydraulic device is in place on the shaft 28, the clamp 12 will be tightened upon the dead end of the cable between the pulley block and drum 29 and the drum 29 will be rotated slowly in a direction to unwind the 'cable so that that portion of the cable between the drum shaft and clamp 12 will be slack as indicated at 30. The drum 11 will then be operated to raise the bit above the bottom of the hole that is bfing drilled, thus imposing the entire weight of the drill bit and its stem upon the hydraulic device which indicates on the gauge 21 the weight or pressure of the bit on the formation. The rotary drilling apparatus will then be started "into operation to efiect rotation of the bit, in a manner well understood in this art. The drum 11 will then be operated to lower the drill bit into engagement with the formation and the driller will note the diminishing pressure on the gauge 21 and sto the drum 11 when the pressure indicated 1s suitable for drilling in the particular stratum that the drill bit is working in. As the bit drills, it will be fed slowly downwardly by releasing the brake 31 on the drum 11 and the driller will continually note the pressure on the gauge 21 so that, if the drill bit is in engagement with rock, it will not be fed so fast as to make too deep a cut, the effect of which would be to cause the drill stemvto be twisted off. Also, if the bit is working in clay, or other similar strata, it is still advisable not to feed it too fast as the clay tends to be broken up in such large lumps as to interfere with the water circulation, and make the bit stick.

From what has been stated above, it will be readily understood that, in setting casing, the casing will be connected with the pulley block 7 by the means illustrated, or by other suitable means, and the casing will be lowered by loosening the brake on the drum 11. If the casing tends to stick, such fact can be readily noted on the gauge, as the pressure will gradually decrease. It is important to note this sticking at the beginning because otherwise the casing would gradually come to a stop and become stuck in the hole and would be difficult to pull out. When the initial sticking of the casing in the hole is observed on the gauge, the casing will be immediately pulled out and the hole enlarged in a manner well understood in this art and then the casing will be lowered again. When the casin shoe strikes the bottom of the'hole the re uction in pressure on the gauge 21 will indicate the fact and the casing may be partially suspended from the top of the well so that the pressure of the upper portion of the casing will not be imposed upon the lower portion which, if it occurred, would" tend to collapse the casing.

If, as sometimes hap ens with the best of care, the casing. shou (1 become stuck so tight that it cannot be raised by the drum 11, the drum 29 will be rotated in a direction to make taut the cable 8 between the drum 29 and the clamp 12, the clamp 12 will then be released from the cable, and

then the drum 29 will be rotated further in the same direction to pull the casing loose, whereupon the clamp will again be tightened on the cable and the drum 29 rotated in a reverse direction to produce the slack 30. This is the advantage of connecting the pull-indicating-means in line with the axis of the drum 29.

We claim:

1. An apparatus of the character described comprising a pulley block, means to connect the pulley block to a part in the well, drums, a cab e rove through the pulley block and connected at its opposite ends with the respective drums, two members in telescopic relation, a'fluid cushion between said members, a gage to indicate the pres sure of said members on the fluid cushion, means to anchor one of said members, and means to releasably connect the other member to the cable between the pulley block and one of the drums.

2. An apparatus of the character described comprising a pulley block, means to connect the pulley block to a part in the well, drums, a cable rove through the pulley block and connected at-its opposite ends with the respective drums, two members in telescopic relation, a fluid cushion between said members, a gage to indicate the pressure of said members on the fluid cushion, means connecting one of said members to one of the drums and permitting rotation of said drum, and means to releasably connect the other member with the cable between the pulley block and, the last named drum.

3; An apparatus of the character described comprising a pulley block, means to connect the pulley block to a part in the well, drums, a cable rove through the pulley block and connected at its opposite ends with the respective drums, a cylinder having a fluid therein, means to anchor the cylinder, at pressure gage connected with the cylinder, a plunger in the cylinder, and means to releasably connect the plunger with the cable between the pulley block and one of the scribed comprising a pulley block, means to connect the pulley block to a part in the well, drums, a cable rovethrough the pulley block and connected atits opposite ends with the respective drums, a cylinder having a fluid therein, means connecting the cylinder to one of the drums and permitting rotation of said drum, a pressure gage connected with the cylinder, a lunger in the cylinder, and means to releasa ly connect the plunger with the cable between the pulley block and the last named drum.

5. An apparatus of the character described comprising a pulley block, means to connect the pulley blockto a part in the well, drums, a cable rove through "the pulley block and connected at its opposite ends with the respective drums, and means releasably con- 'nected with the cable between the pulley 'block and one of the drums to indicate the amount of pull exerted on the cable by the part in the well connected therewith.

- 6. An apparatus of the character described comprising a pulley block, means to connect the pulley block to a part in the well, drums, a cable rove through the pulley block and connected at its opposite ends with the respective drums, and means connected with one of the drums and permitting rotation of said drum and releasably connected with the cable between the pulley block and the last named drum to indicate the amount of pull exerted on the cable by the part in the well connected therewith.

Signed at Los' Angeles, California this 17th day of January, 1924.

HOLMES H. HENSHAW. WILLIAM H. TAYLOR. 

